Abstract:

In this study, the feasibility of using an industrial fluidized bed furnace to perform low-temperature
thermochemical treatments of austenitic stainless steels has been studied, with the aim to produce expanded
austenite layers with combined wear and corrosion resistance, similar to those achievable by plasma and
gaseous processes. Several low-temperature thermochemical treatments were studied, including nitriding,
carburizing, combined nitriding-carburizing (hybrid treatment), and sequential carburizing and nitriding.
The results demonstrate that it is feasible to produce expanded austenite layers on the investigated
austenitic stainless steel by the fluidized bed heat treatment technique, thus widening the application
window for the novel low-temperature processes. The results also demonstrate that the fluidized bed
furnace is the most effective for performing the hybrid treatment, which involves the simultaneous
incorporation of nitrogen and carbon together into the surface region of the component in nitrogen- and
carbon-containing atmospheres. Such hybrid treatment produces a thicker and harder layer than the other
three processes investigated.